Mark Lennihan / AP file

Visitors look over the waterfalls at the National September 11 Memorial and Museum on Feb. 25 in New York.

NEW YORK -- Faced with hefty operating costs, the foundation building the 9/11 museum at the World Trade Center has decided to charge an admission fee of $20 to $25 when the site opens next year.

The exact cost of the mandatory fee has not yet been decided.

Entry to the memorial plaza with its twin reflecting pools will still be free.

The decision to charge for the underground museum housing relics of the Sept. 11, 2001, terror attacks has been greeted with dismay by some relatives of 9/11 victims.

"People are coming to pay their respects and for different reasons," said Janice Testa of Valley Stream, whose firefighter brother Henry Miller Jr. died at the twin towers. "It shouldn't be a place where you go and see works of art. It should more be like a memorial place like a church that there's no entry fee."

Testa was visiting the memorial Saturday with relatives from Florida.

The memorial plaza opened in 2011 on the 10th anniversary of the terror attacks, but disputes over funding have pushed the museum's opening back to spring 2014.

With the cost of operating the memorial and museum projected to be $60 million a year, the memorial foundation voted at its board meeting last week to charge a mandatory admission fee for the museum.

"This is something that is going to be important and is going to be worth the expenditure," Joseph Daniels, president of the National September 11 Memorial and Museum, said Saturday.

Daniels said the museum will be free during certain hours every week and will offer student and senior discounts.

Foundation officials had considered an optional donation but rejected the idea.

"We decided that it's more fiscally prudent to have a straight ticket charge," Daniels said.

Debra Burlingame, a foundation board member whose brother was the pilot of one of the hijacked planes, said the trade center site is expensive to build on and to protect.

"The World Trade Center site remains a target of interest among terrorists, so the security has to be robust and relentless," Burlingame said in a phone interview. "There's a big price tag on that.

"Would we like to be able to say this is free? Absolutely," Burlingame added. But she called it "irresponsible to hope that year after year we have donations that will cover an expense like security."

Some visitors to the memorial were divided about charging admission to the museum.

Retired school psychologist Valerie Cericola of Lavalette, N.J., said the entry fee sounded fair.

"You need to keep it open, you need to keep it running," she said. "It's an expense."

But Jennifer Reyes, a friend of Cericola's daughter who was born on Sept. 11, 2001, said the museum should ask for an optional donation.

"I think a donation like $10 would be good," Jennifer said.

AP radio correspondent Julie Walker contributed to this report. 

Related: Images of the World Trade Center site from PhotoBlog

LOS ANGELES — Robbers wearing masks and goggles broke into a mining museum in California in broad daylight and stole gold and gems valued at up to $2 million, authorities said.

Although no-one has been identified in connection with the burglary, California investigators are searching for at least two suspects.

The masked men broke into the California State Mining and Mineral Museum in Mariposa, California, on Friday afternoon with pickaxes and forced employees into one end of the building, the Los Angeles Times reported, citing a state parks spokesman.

Read the story on NBC station KCRA

But the thieves didn't get away with the biggest prize of all — the nearly 14-pound Fricot Nugget, a giant crystalline gold mass unearthed in the California Gold Rush era. The robbers triggered an alarm as they tried to break into the iron safe where it was held.

According to the museum's website, the Fricot Nugget was discovered in the American River in Northern California in 1864 and is the largest intact mass of crystalline gold remaining from the Gold Rush era.

John Palmer / California State Parks via AP

Authorities say thieves made off with an estimated $2 million in gold and precious gems during the armed robbery at the California State Mining and Mineral Museum, seen in this 2009 photo.

The California State Mining and Mineral Museum is described on its website as offering visitors the chance to explore the variety of the state's mineral wealth and view "breathtaking gems and minerals from around the world."

The California department of parks and recreation issued a statement on Monday saying the museum would be closed "until further notice while repairs are completed."

The statement added that the museum is taking an inventory of the stolen items this week, which will allow it to confirm what was taken and exactly how much the items were worth.

The Los Angeles Times reported that the museum had moved its treasures to an undisclosed location in the meantime.

The burglary was the second theft of this year involving rare, valuable minerals in Northern California. Chunks of gold were stolen from the Siskiyou County courthouse in February.

No suspects have been identified and authorities are investigating whether there is a connection between the two incidents.

NBC News staff and Reuters contributed to this report.

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John Brecher / msnbc.com

A crowd in the Georgetown neighborhood of Seattle watches NASA's Super Guppy aircraft approach Boeing Field, carrying a key piece of a space shuttle mockup that will go on display at Seattle's Museum of Flight.

SEATTLE — It may not be a real space shuttle, but it's ours.

Today NASA delivered a key piece of the mockup that astronauts used for space shuttle practice to the Museum of Flight in Seattle, my hometown. And it arrived aboard one of the most ungainly-looking airplanes ever built. The wingless mockup is known as the Full Fuselage Trainer, or FFT. The plane has a nickname that's more colorful: the Super Guppy.

The Super Guppy looks more like a Super Whale. The wide-body turboprop airplane has a cargo hold that's been built up into a bulbous shape, specifically to carry big stuff for outer space. Only five of the Guppies were ever produced, and they were used to cart spacecraft components around for the Gemini, Apollo, Skylab and shuttle programs. This Super Guppy is the only one of its kind still flying, and this week's odyssey with the most important piece of the Full Fuselage Trainer is one of the highest-profile flights the plane has ever taken.

For decades, the plywood-built FFT sat in a building at NASA's Johnson Space Center in Houston. The crew compartment — the part of the structure that was flown to Seattle today — was outfitted with all the buttons, switches, cockpit displays and middeck lockers that the real shuttles had. None of those gadgets worked, but they helped the astronauts get familiar with the layout before they started handling the real controls. Astronauts could also practice how they'd get out of the shuttle in the event of a landing-strip emergency.

With the end of the space shuttle era, NASA's Johnson Space Center no longer needed the FFT, so the space agency decided to donate it for display. The Seattle museum made a play for one of the flown shuttles, and even built a shuttle-sized, 15,500-square-foot Space Gallery to display it in. But Seattle lost out to Florida, California, New York and the "other Washington" in the competition for Atlantis, Endeavour, Enterprise and Discovery. The Full Fuselage Trainer served as the consolation prize.

Most of the FFT's plywood parts could be shipped up by traditional means for later assembly, but the shuttle crew compartment had to be transported all in one piece. That's why NASA's Super Guppy was called into service.

The airplane has a 25-foot-high, 25-foot-wide, 111-foot-long cargo compartment — big enough to hold the mockup's most awkward piece, even when it's bound up in shrink wrap and a protective steel frame. Over the past couple of days, the Super Guppy has been making a journey from its home at Ellington Air Force Base in Texas, over to California, and then up to Seattle at a top speed of around 200 knots. It wasn't exactly a record-setting pace — but what the Super Guppy lacks in speed, it more than makes up for in the "What the Heck Is That?" department.

The Guppy flew over my hometown and its surroundings with a Seattle-born astronaut, Greg Johnson, at the controls. Then it floated down to a landing right in front of the museum, which is adjacent to Boeing Field. One of the commentators at the museum called it a "beautifully ugly airplane."

Washington Gov. Christine Gregoire pointed to the craft with pride as the sky spit down rain. "When we get together in Washington state, we can land the big whale right behind me," she said.

Museum of Flight

NASA's Super Guppy and a chase plane fly above the mostly cloudy skies of Seattle.

Museum of Flight

After its touchdown at Seattle's Boeing Field, the turboprop-powered Super Guppy taxis over to the Museum of Flight next door.

Museum of Flight

The entire front of the Super Guppy swings open to reveal the cargo inside.

Museum of Flight

The 65,000-pound Tunner 60K aircraft cargo loader and transporter rolls toward the Super Guppy.

Museum of Flight

The cargo compartment for the Full Fuselage Trainer, wrapped in protective plastic, has been taken out of the Super Guppy for a short ride on the Tunner transporter to its new home in the Museum of Flight's Charles Simonyi Space Gallery.

Several thousand onlookers watched as the Super Guppy's entire front opened up to the side like a four-story-high door. 

"It's really cool that it's actually able to fly," Allison Kirkman, a 10-year-old student at Spirit Ridge Elementary School in Bellevue, Wash., told me as she watched from the tarmac. "It's an amazing plane, and how they built it is cool, too."

The shrink-wrapped shuttle crew compartment was moved out of the wide-yawning Super Guppy onto a 65,000-pound mobile transporter, then rolled over to the museum's Charles Simonyi Space Gallery. Over the next couple of months, the shuttle mockup will be assembled in a place of honor, alongside a Russian Soyuz capsule and a prototype lander that was used in Blue Origin's spacecraft development program. Museumgoers like Kirkman will be able to walk through the shuttle mockup's cargo bay — and they might even be able to crawl through the crew compartment, just like the astronauts did.

Kids, prepare to be amazed ... again.

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

Philip Sears/Reuters

Corinne Hershkovitch, legal representative of the family of Federico Gentili di Giuseppe, and officials stand next to the painting "Christ Carrying the Cross" by Italian artist Girolamo de' Romani after signing papers to return it to its rightful owners in Tallahassee, Florida.

TALLAHASSEE, Fla. -- A painting – nearly five centuries old and worth millions - that was taken by the Nazis in World War II has been returned to the heirs of its original Jewish owner by U.S. officials.

"Christ Carrying the Cross Dragged By A Rascal" by Italian artist Girolamo de' Romani was stolen during the occupation of France from Frederico Gentili di Giuseppe, an Italian Jew who had lived in Paris, Reuters reported.

He died of natural causes in 1940, a month before the Nazis invaded, and his children and grandchildren had already fled the country.

The painting was one of 70 items taken from his collection, Reuters said. It depicts Christ crowned in thorns, carrying a cross and dressed in a copper-colored silk robe, and dates back to circa 1538.

The collection was sold by the French Vichy government – allowed by the Nazis to run parts of France - in 1941 and Gentili's grandchildren filed suit in 1997 to get it back, according to the news service.

The painting had found its way to the Pinacoteca di Brera museum in Milan, Italy, which then loaned it to the Mary Brogan Museum of Art and Science in Tallahassee, Florida.

'Right a wrong'
Based on a tip from an employee of Christie's auction house in June 2011, Interpol investigators last summer alerted U.S. officials that the painting may have been stolen, Reuters reported.

Last September, U.S. Attorney Pamela Marsh ordered the Brogan museum to hold the painting instead of returning it to Italy, saying the federal government believed it rightfully belonged to the man's family, according to The Associated Press. It had been under the protection of the U.S. government since November.

"Seventy years is a very long time … But it shows that it is never too late to right a wrong,” U.S. Homeland Security Investigations Special Agent Susan McCormick told reporters Wednesday.

The piece is one of hundreds of thousands of works of art stolen from Jewish families throughout Europe by the Nazis. It is among nearly 2,500 works of art and antiquities that Homeland Security Investigations officials have repatriated to 23 countries since 2007.

Gentili's grandson, Lionel Salem, told reporters by telephone on Wednesday that the six heirs plan to sell the work, which he said was due to be auctioned at Christie's in New York on June 6. The painting has been insured for $2.5 million.

"For a cake, it is relatively easy cutting it into six, not totally easy but quite easily," Salem said of the family's decision to sell. "But for a painting, you see, it is more difficult."

Marsh hailed the outcome of the investigations.

"This result happened only because people were courageous and willing to step up and do what they knew was right and good," she said, according to The Associated Press.

Reuters and The Associated Press contributed to this report.

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Shane Dunlap / The Evening Sun

A John Wilkes Booth bobblehead doll is shown for sale alongside an Abraham Lincoln bobblehead at the Gettysburg Museum & Visitor Center.

The Abraham Lincoln Presidential Library and Museum in Springfield, Ill., is no longer selling a bobblehead doll of Lincoln’s assassin at its gift shop, the Chicago Tribune reported.

The move follows news that the Gettysburg National Military Park in Pennsylvania pulled the John Wilkes Booth dolls from its stores earlier this week, Lincoln museum spokesman Dave Blanchette told the Tribune.

Blanchette told the newspaper that the museum’s administrators has not received any complaints about the dolls, but that they agreed with the Gettysburg Park’s assessment that they were not appropriate for sale. “It seems to be in bad taste,” he said.

"This was the first time that we really took a hard look at having these items for sale," Blanchette told the Tribune.

The dolls of Booth with a handgun were removed from Gettysburg shelves on Saturday, a day after a reporter for Hanover's The Evening Sun newspaper asked about them, officials said.

"On rare occasions, there's an item that might cause concern, and obviously the bobbleheads appeared to be doing that," Gettysburg Foundation spokeswoman Dru Anne Neil said Tuesday.

The dolls were available for only about a week before the park superintendent, the foundation president and the bookstore manager decided they shouldn't be for sale, Neil said.

The Booth dolls, which are about 7 inches tall and come in boxes that look like the inside of the theater where Lincoln was killed, sell online for about $20 each. They have proved to be popular, as more than 150 of the original run of 250 have been sold, and more are being made, Kansas City, Mo.-based manufacturer BobbleHead LLC said.

"There's a market there," sales manager Matt Powers said. "We like to let the customer decide if it's a good item or not."

The company sells dolls of many controversial figures, including Kim Jong-il, the recently deceased leader of North Korea, The Evening Sun reported. But Powers told the paper, "I don't think we'd do Hitler."

Confederate sympathizer Booth shot Lincoln at Ford's Theatre in Washington in April 1865, as the Civil War was ending. He fled and was tracked into Virginia, where he was killed.

The Associated Press contributed to this report.

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